Cloning, Expression, and Functional Characterization of Two Highly Efficient Flavonoid-di-<i>O</i>-glycosyltransferases ZmUGT84A1 and ZmUGT84A2 from Maize (<i>Zea mays</i> L.)

Abstract

The maize ( Zea mays L.) glycosyltransferase family 1 comprises many uridine diphosphate glycosyltransferase (UGT) members. However, UGT activities and biochemical functions have seldom been revealed. In this study, the genes of two flavonoid di- O -glycosyltransferases ZmUGT84A1 and ZmUGT84A2 were cloned from maize plant and expressed in Escherichia coli . Phylogenetic analysis showed that the two enzymes were homologous to AtUGT84A1 and AtUGT84A3. The two recombinant enzymes showed a high conversion rate of luteolin to its glucosides, mainly 4′,7-di- O -glucoside and minorly 3′,7-di- O -glucoside in two-step glycosylation reactions in vitro . Moreover, the recombinant ZmUGT84A1 and ZmUGT84A2 had a broad substrate spectrum, converting eriodictyol, naringenin, apigenin, quercetin, and kaempferol to monoglucosides and diglucosides. The highly efficient ZmUGT84A1 and ZmUGT84A2 may be used as a tool for the effective synthesis of various flavonoid O -glycosides and as markers for crop breeding to increase O -glycosyl flavonoid content in food.